The invention concerns a position detection device for detecting several positions of a structural component, which move along a guide track, by means of a sensor device that can be fixed to the guide track and that comprises at least a first position sensor element extending along a partial length of the guide track for continuous position detection.
DE 201 06 298 U1 discloses such a position detection device for a pneumatic linear drive in which position sensor elements designed as path measuring systems are arranged along the two end areas of the guide track for the continuous detection of positions in these end areas. Each position sensor element comprises a sensor signal connector designed as a threaded connector for the connection of appropriate sensor cables. The two sensor cables and other optional sensor cables in the case of other position sensor elements along the guide track require complicated installation. The plurality of sensor cables often proves to be problematic, especially in the case of moving devices. In addition, problems and defects can occur if the sensor cables are not clearly identified.
One problem addressed by the present invention is to create a position detection device that requires only one sensor cable, can detect several positions, is simple, economical and can be readily assembled.
The invention solves this problem in that the first position sensor element is permanently connected via a flexible signal conductor arrangement to at least one second position sensor element and that one of the sensor elements comprises a sensor signal connector for the signals of all sensor elements.
The position detection device of the invention has the advantage that, on the one hand, only one sensor cable is required for at least two position sensor elements and that these position sensor elements can be positioned as desired in a simple manner by the flexible signal conductor arrangement connecting them and their position change without electrical connections having to be set up or modified. This results in a very robust arrangement that is not susceptible to problems and that can also be made moisture-proof in a relatively simple manner.
The sensor signal connector is advantageously designed as a plug connector or a threaded connector.
The second position sensor element can also be designed as a position sensor element for continuous position detection extending along a partial range of the guide track; however, it is frequently sufficient to carry out the more complicated path measuring only at one end area of the guide track while on the other end area a simple position switch element for detecting the end position is sufficient. As a consequence of its larger geometric extension, the first position sensor element is advantageously provided with the sensor signal connection, especially if the second position sensor element is designed as a position switch element.
The position sensor elements are preferably designed to be sensitive to magnetic fields whereas the movable component is or carries a permanent magnet. A Reed switch or Hall switch is preferably suitable as the position switch element.
In order to facilitate the installation and wiring, the flexible signal conductor arrangement advantageously comprises a variable linear extension and is designed especially as a spiral cable.
For fixing to the guide track, the position sensor elements are designed to be pushed or inserted into a groove, which runs along the guide track, preferably designed as a T-groove, in which case the position sensor elements have a corresponding T-shaped cross section. This design also contributes to a rapid and simple fixing of the position sensor elements.
The position detection device is particularly suited for a linear drive formed by the movable component and the guide track. The movable component is preferably designed as a piston that can move in a cylinder.
For positioning and fixing in the desired positions the position sensor elements comprise means for a variable fixing to the guide track that are designed in particular as fixing screws. This also makes possible a rapid and simple repositioning.
A signal preparation device and/or signal evaluation device and/or a bus terminal is/are advantageously arranged in one of the two position elements, preferably in the position sensor element provided with the sensor signal connection.
An embodiment example of the invention is shown in the drawing and explained in detail in the following description.